Dredge cutterheads are generally conical with a multiplicity of hard rock cutting teeth or replaceable edges projecting outwardly from a plurality of spaced helical support vanes or blades disposed about its conical surface. The cutterhead normally has a hub which fits around a shaft and provides the torque which turns the cutterhead in its operation of dredging the bottom of waterways. The cutterhead encounters all kinds of material, including rock, which must be removed.
For the purpose of digging in rocky ground the cutterhead is fitted with teeth of high hardness and high impact properties;for the purpose of digging in soft to medium-soft ground the cutterhead is provided with edges of moderate hardness welded to the leading edge of the cutterhead blades. The service life of such welded edges is not as long as that of the hard teeth. The hard teeth extend radially a substantial distance ahead of the blade and do not perform efficiently in the soft-to-medium earth. Accordingly, it is most desirable to provide a cutterhead employing teeth of high hardness and wear resistance arranged in such a manner as to be efficient for digging in soft-to-medium soils and also to provide the advantages of easily replaceable forward edges.
The most common variety of replaceable tooth for a dredge cutterhead embodies a tapered shape which is attached by an adapter to the cutterhead blade such that the point of the taper is directed at the surface which is to be cut and the longitudinal axis of the tooth, generally passes through the centroid of the cutter blade section and is generally at an angle with respect to the profile plane of the cutterhead from the point of the tooth so as to provide an efficient transmission of power to the tooth with a minimum of breaking force. A replaceable tooth assembly is disclosed in U.S. Pat. No. 4,891,893, for example.
There is, of course, always the problem of realigning the tooth in the proper direction with respect to the cutterhead and welding the tooth into a fixed realignment. A novel assembly has been developed which permits a precise alignment for replacing the adapter, regardless of whether the adapter has been worn or broken.
It is an object of this invention to provide an improved assembly for mounting an adapter onto a cutterhead. It is another object of the invention to provide a system for accurately mounting an adapter and obtaining a desired alignment without special or laborious efforts. Still other objects will appear from the more detailed description which follows.